Aryl-urea thickened greases



United States Patent 2,710,839 ARYL-UREA THICKENED GREASES Edward A.Swakon, Hammond, and Cecil G. Brannen, Munster, Ind., assignors toStandard Oil Company, Chicago, 111., a corporation of Indiana NoDrawing. Application November 1, 1952, Serial No. 318,321

14 Claims. (Cl. 25249.6)

The present invention relates to novel lubricant greases and to themethod of preparing same. More particularly, it relates to novel greasescomprising a lubricant vehicle thickened with certain high meltingaromatic ureido and amido compounds. Greases of this type, particularlythose wherein the lubricant vehicle comprises a silicone polymer oil,have demonstrated exceptional stability and lubricity at elevatedtemperatures.

As lubricants are required to perform at higher and higher temperaturesbecause of increased speeds of engines and machines, the advent of jetpropulsion, atomic energy as a source of power, etc., it has becomeincreasingly diflicult to prepare greases fulfilling the require mentsof such lubricants. In attempting to provide such greases, the art hasprogressed from the use of petroleum lubricant vehicles thickened withmetal soaps of long chain fatty acids, e. g. lithium hydroxystearate, tomore thermally stable synthetic lubricating oils such as the aliphaticdiesters of dicarboxylic acids, silicone polymers, etc., thickened withsuch soaps or inorganic materials such as silica gels. The progress ofthickener research has not in general, however, kept pace with thedevelopment of lubricant vehicles. And at temperatures as high as 400 to450 F. there are few if any greases available which will retain theirconsistency and lubricity for any substantial period of time.

In recent years various synthetic lubricant vehicles, e. g. thesilicones, fiuorocarbons, etc., have been found to be potentiallyvaluable for use in greases employed at very high temperatures becauseof their thermal stability and relatively low volatility. Unless,however, a thickener having substantially the same degree of thermalstability is available to produce a grease fromssuch an oil, they are oflittle use. It has now been found'that certain very high meltingaromatic urea s,:,di-.ureas,.amides, and di-amides, all of which containat least one o RNHil radical, wherein R isan aryl radical, and which mayhereinafter be referred to broadly as arylcarbamyl compounds, may beemployed to thicken silicone polymer oils, as well as other knownlubricant vehicles, to produce greases which are stable and displayexcellent lubricant propertiesat high temperatures. Whereas siliconepolymer oils are particularly preferred for use in greases employed attemperatures as high as about 450 F, other lubricant vehicles, eithernatural or synthetic, may also be thickened with these materials toproduce greases of particular utility between about 250 F. and

about 400 It. is aprirnary object of therpresent invention to providelubricant greases which-are stable: and give excellent lubrication atelevated temperatures. A further object is to provide areadilyjproducible series:of:;greases embodying a novel class ofthickening agents capable of yielding lubricants particularly suitablefor use at temperaturesbffrom -about'250 "'F. to about 450 F. A

particular object of the present invention is to provide greases whichare effective lubricants at temperatures as high as about 450 F. forsubstantial periods of time. These and additional objects will beapparent from the following detailed description.

We have found that lubricating vehicles such as silicone polymer oils,mineral lubricating oils derived from petroleum, synthetic lubricatingoils such as polyalkylene glycols and their derivatives, high molecularweight esters of dicarboxylic acids, etc. and preferably the siliconepolymer oils may be thickened to grease consistency by the additionthereto of from 5 to 70% and preferably from about 10 to about 50% of anarylcarbamyl compound selected from the group consisting of aromaticureas, di-ureas, amides, and di-amides. Thus, in accordance herewith,arylcarbamyl compounds having the following empirical structure arecontemplated as thickening agents in the art of grease manufacture:

O a minmen In .the above formulae, R, R and R" represent aryl or alkylaryl radicals. With the exception that R" is necessarily a divalentradical, e. g. phenylene, biphenylene, naphthylene, etc., these radicalsmay be the same ordifferent, e. g. phenyl, biphenyl, naphthyl, etc. ineach com pound. The aryl .or alkyl aryl radicals may be substitutedradicals containing various reactive ,substituents such as hydroxy,carboxy, halo, nitro-, etc.

Examples of amides and di-amides which have been foundto yield excellentgreases when employed as thickeners are N-benzoyl-4-aminobiphenyl,N,N'dibenzoylbenzidine, N,N'-dibenzoyl-p-phenylenefdiamine and N,N-bis-(p-nitrobenzoyl)-benzidine. Such compounds may 'be readily preparedby techniques well known to the art, e. g. by reaction of an aromaticamine or diamine such as phenylene-diamine, aniline, benzidine, etc.,with an aroyl-halide, e. g. benzoyl chloride. 'Diamides such as may beprepared by reacting an aromatic monoamine, e. g. aniline, with an aroylhalide such as a phthalyl chloride, may likewise be employed inaccordance herewith. These compounds maybe employedlalone or-incombination to thicken oleaginous vehicles to grease consistency,

'Examples of various ureas and di-ureas which have been found ,useful asthickeners in accordance herewith :are p-carboxyalfl-diphenylurea;CPrChl rmLB-diphenyI- urea; 1,3-di-(.l-naphthyl)-urea;4,4-bis-[3-(p-biphenylyl)- llreido] -biphenyl; 1- (p-carboxyphenyl) -3-(p-biphenylyl an amine or diaminesuchas aniline; benzidinephenylenediamine, etc. with an isocyanate of benzene, diphenyl, etc. Itshould be understood that the specific aryl carbamyl compounds set forthabove are enumerated for purposes of illustration and not of limitation.Compounds of this class may be employed alone or in combination withother such compounds to thicken oleaginous vehicles in accordanceherewith.

Greases prepared with thickeners of the type described above,particularly those prepared from silicone oil, are exceptionally stableat elevated temperatures with those prepared from ureido compounds beingslightly superior to those prepared from amide type thickeners.

The silicone polymer oils which may be employed in accordance with thepresent invention are those falling substantially within the lubricatingoil viscosity range. In general, such oils have the following unitstructure:

wherein R and R represent substituted or unsubstituted alkyl, aryl,alkylaryl, arylalkyl or cycloalkyl radicals.

Such compounds may be produced by well-known meth ods, e. g. thehydrolysis of dialkyldichlorosilanes or dialkyldiethoxysilanes with asuitable chain stopper, e. g. a trisubstituted mono-chlorosilane. Forpurposes of the present invention, those polymers which are high boilingliquids within the lubricating oil viscosity range are suitable, thesegenerally possessing a viscosity at 100 P. which is within the range offrom about 25 to about 3500 S. S. U. It is preferred, for purposeshereof, to employ such oils as have a viscosity at 100 F. of from about300 S. S. U. to about 1250 S. S. U. Such products are generallycolorless and inert, have a very low volatility and undergo relativelyslight change in viscosity for a given change in temperature. Relativelycommon oils of this type are dimethylsilicone polymer,phenylmethylsilicone polymer, chlorophenylmethylsilicone polymer, etc.,it being preferred to employ the phenylmethylsilicone polymer inaccordance herewith. Methods of preparing such compounds are taught innumerous patents, e. g. U. S. 2,410,346, U. S. 2,456,496, and in theliterature such as Chemistry of the Silicones by Rochow, page 61, etseq. A particularly desirable phenylmethylsilicone polymer for use inaccordance with the present invention is Dow-Corning 550 silicone fluid,a product of Dow-Corning, Inc., which has a viscosity at 100 F. of about300 to about 400 S. S. U.

Other oleaginous vehicles which may be employed herewith are, forexample, mineral oils in the lubricating oil viscosity range, i. e. fromabout S. S. U. at F.- to about 300 S. S. U. at 210 F. These mineral oilsare preferably solvent extracted, to substantially remove the low V. I.constituents, e. g. aromatics, with phenol, fur-- fural,B,B'-dichlorodiethylether (Chlorex), liquid S02, nitrobenzene, etc.Synthetic lubricating oils resulting from polymerization of unsaturatedhydrocarbons or other oleaginous materials within the lubricating oilviscosity range such as high molecular weight polyoxyalkylene compoundssuch as polyalkylene glycols and esters thereof, aliphatic diesters ofdicarboxylic acids such as the butyl, hexyl, 2-ethylhexyl, decyl,lauryl, etc. esters of sebacic acid, adipic acid, azeleic acid, etc.,may be thickened by the aryl carbamyl compounds of the present inventionto produce excellent greases. Polyfluoro derivatives of organiccompounds, particularly hydrocarbons, in the lubricating oil viscosityrange have shown excellent promise when thickened with compounds of thepresent invention.

Greases cf the present invention may be produced by one of the followingmethods:

(1) The thickener may be prepared apart from and then admixed with thelubricant vehicle and milled in a colloid mill, 3-rol1 mill, etc.

(2) The thickener may be formed in situ in the oil by introducing thereactants and the desired amount of lubricant vehicle, heating to about450 F. for a relatively short time, c. g. from about five minutes to anhour to drive oif volatile by-products, and then cooling and milling themixture.

(3) As a slight modification of method 2 above, a solvent such asdioxane may be employed as a diluent and mutual solvent for thereactants. The solvent is thenv evaporated and the grease is milled,etc. substantially as set forth.

(4) As a step in any of the above three methods, it has been found, whenemploying a silicone vehicle, that improved properties may be impartedto the grease by heat-treating the grease mixture, i. e. subjecting sameto a temperature of about 450 F. for at least about half an hour andpreferably longer, e. g. from about 1 to 20 hours. Prolonged heating atsuch temperature may evaporate a portion of the lubricant vehicle; thisloss should be replaced and then the mixture should be milled. Ifdesired, the heating and readdition of vehicle may be repeated beforemilling.

Table 1 Hours Be- Thickener Class g gfi Egg-s ggg i g Remarks 0N-Benzoyl-p-aminobenzoic acid RtiiNHR' 33 (3) (4) 337 #1 o; #2 gradegrease of excellent tex- 0 0 e. N,N-Dibe zoy1benz1d1 e RtiNHR'NHii R 26188 2 33; fl sgg i g g e a sm g gg 4,4',b1s(3-b1pheny1ylureldo)-bipheny1RN'H N'HW'NHi'JNHR 20 (3) (4) 437 Ggc id appearing #2 grade grease- O oghly stable. D0 RNH( JNHR"N'HglNHR 18 (3) (4) 448 DO.

0 0 4,4 b1s[3 (2,5 diehloropheny1-)ureido1bt- RNH NH R"NHgNHR 25 (3) 435smooth uttery 0r #2 grade phenyl. o grease. p-carboxy-L3-diphenylureaRNHgNHR' 29 (3) (4) 653 Good appearance-#2 grade grease.

0 Do RNH ()NHB. 23 (3) (4) 445 D0.

0 O 4,4'-b1s(3-p-tolylureido)-btphenyl RNHi'JNHW'NHi'JNHR 20 (3) (4) 481Smooth buttery #2 grease.

'N. L. G. I. consistency grades.

The method'of forming the-thickener in 'situ in the lubricant vehicledesci ibd aboveis claimed in our'co- *pending serial No. 392,996filed'November 18, 1953.

In Table 1 are 'setforththe data obtained on certain greasescomprisingDCSSO (phenylmethyl silicone polytreated precision204iN=ormaeHolfman bearing, is sub-' jected to a temperature of 450 F.in an oven, the other bearing, a standard New Departure 204 bearing, isat room temperature. Temperature is determined by a thermocoupleinserted in the grease between the races of the bearing in the oven.Failure is adjudged to occur when (1) the temperature in the-testbearing reaches 470 F. or higher, (2) wattage inexcess of 300% of normalWattage as required, or (3)the' bearing does not turn over at thebeginning of a test cycle, (the test iscondu'cted in cycles of 20 hoursoperating and 4 hours at rest).

In Tables 2and'3,lbelow, are set forth data on greases comprisinglubricant-vehicles other than silicone oil thickened withp-carbox'yl-1,3 diphenyl-urea and '4,4-bis-(3- phenylureido) -b'iphenyl,respectively.

1 C1H 5COOCHflCHzOCHQZCHzOCOC7H15 where z is such as to result inamaterial within the lubricating. oil viscosity range.

2 The composition of this 'v'ehicle'was asfollows: 90.6%di-2-ethylhexylvsebacate, 3:9 commercialacrylimbase V. I. improver, 5.0% tricresylphosphate, 0.001 U of silicone anti-foam, and 0.5% phenothiazine. 3Kaufmann micropenetration.

."Tdble 13 Percent I Method Lubricant Vehicle y Consistency of ThickenerPrep Benzyl benzoate 30 54 (3) A. I. F. Extracted Oil 25 47 (3)Fluorocarbon Oil 3 12 95 (3) 1 Kauimann micropcnetration. 2 Petroleumoil of high aromatic content. 3 Kel-F Polymer N o. 40 (product of The M.W. Kellogg 00.).

Greases of the type set forth in the above tables are stable at hightemperatures although generally somewhat less stable than those preparedwith silicone oil as the lubricant vehicle. Accordingly, they are moresuitably employed at temperatures in the range of from about 250 F. toabout 400 F. It should be understood, in any event, that While thegreases of the present invention are particularly suitable for use attemperatures above 250 F. they are also extremely useful at lowertemperatures. Surprisingly, greases of this type, e. g. a siliconethickened with p-carboxy-1,3-diphenyl urea, having exhibited exceptionalproperties at extremely low temperatures. Thus, as indicated in thefollowing table, a grease comprising D. C. 550 silicone oil thickenedwith 25% by weight of p-carboxy-1,3-diphenyl urea (Grease A) exhibitssubstantially better low temperature properties than a grease comprisingD. C. 550 thickened with 20% by weight of lithium-12-hydroxy stearate(Gerase B). It will be noted that of the two greases the grease of thepresent Table 4 Apparent Viscosity Data 1 Low Temperature Torque 2 (-40"F.

under 2,000 gm.-cm.

load) Apparent Viscosity (puises) Penetration 3 (Worked) TemperatureGrease A 1 Method and apparatus are described in ASTM Standards onPetroleum Products and Lubricants Method .D1092-51.

Z See Specification MIL G3278 25 August 1950.

3 Same reference at above, method D217-48.

As is well known the lithium I'IZ-hydroxy *steaiate greases exhibitlower.apparent'viscosities atany .given shear rate than other metal basesoaps, e. g. calcium, sodium, etc. The data in the abovetable clearly.indicate that the urea thickened grease'may be'employed at'ev'en lowertemperatures than the lithium soap grease. iThese greases may have addedthereto antioxidants, oiliness agents, extreme pressure additives, etc.Withoutiniany'way departing fromthe scope of 'the present invention.

Having'thus described our invention, what we claim as novel and desireto protect by LettersP-atent isde fined by the following claims:

1. A lubricantgrease comprising a lubricant-vehicle thickened with from5 to 70% by 'weight of'at least one aryl-carbarnyl compound melting=above about 250 P. which compound is selected from the'group consistingof Grease B 19. 5 330 RNHONHR A and wherein R and R representhydrocarbon radicals containing no more than 12 cyclic carbon atoms,which radicals are selected from the group consisting of aryl, alkylaryl, substituted aryl, and substituted alkyl aryl radicals, and R"represents a divalent hydrocarban radical, containing no more than 12cyclic carbon atoms, which radical is selected from the group consistingof arylene, alkyl arylene, substituted arylene, and substituted alkylarylene radicals.

2. The lubricant grease of claim 1 wherein the lubricant vehiclecomprises a silicone polymer oil in the lubrieating viscosity range.

3. The lubricant grease of claim 1 wherein the lubricant vehiclecomprises an acyclic ester of an aliphatic dicarboxylic acid in thelubricating oil viscosity range.

4. The lubricant grease of claim 1 wherein the lubricant vehiclecomprises a polyoxyalkylene compound in the lubricating oil viscosityrange.

5. The lubricant grease of claim 1 wherein the lubricant vehiclecomprises a mineral lubricating oil derived from petroleum.

6. The lubricant grease of claim 1 wherein the lubricant vehiclecomprises a polyfluoro-compound in the lubricating oil viscosity range.

7. A lubricant grease comprising a lubricant vehicle thickened with from5 to 70% by Weight of at least one aryl carbamyl compound melting aboveabout 400 P. which compound is selected from the group consisting of (H)RCNHEV'NHPIR wherein R and R represent hydrocarbon radicals containingno more than 12 cyclic carbon atoms, which radicals are selected fromthe group consisting of aryl, alkyl aryl, substituted aryl, andsubstituted alkyl aryl radicals, and R" represents a divalenthydrocarbon radical containing no more than 12 cyclic carbon atoms,which radical is selected from the group consisting of arylene, alkylarylene, substituted arylene, and substituted alkyl arylene radicals.

8. A lubricant grease comprising essentially a silicone polymer oil inthe lubricating oil viscosity range thickened with from about to about70% by weight of p-carboxy- 1,3-diphenylurea.

9. A lubricant grease comprising essentially a silicone polymer oil inthe lubricating oil viscosity range thickened with from about 5 to about70% by weight of N-benzoylp-aminobenzoic acid.

10. A lubricant grease comprising essentially a silicone polymer oil inthe lubricating oil viscosity range thickened with from about 5 to 70%by weight of N,N'-dibenzoylbenzidine.

11. A lubricant grease comprising essentially a silicone polymer oil inthe lubricating oil viscosity range thickened with from about 5 to 70%by Weight of 4,4'-bis- [3 (p-biphenylyl) -ureido] -biphenyl.

12. A lubricant grease comprising essentially a silicone polymer oil inthe lubricating oil viscosity range thickened with from about 5 to byWeight of 4,4'-bis- [3 (2, S-dichlorophenyl) -ureido] -bipl1enyl.

13. The method of preparing a lubricant grease which comprises milling amixture comprising essentially a lubricant vehicle and from about 5% toabout 70% by weight of an aryl carbamyl compound melting above about 250F. selected from the group consisting of O RNHENHR and wherein R and R'represent hydrocarbon radicals containing no more than 12 cyclic carbonatoms, which radicals are selected from the group consisting of aryl,alkyl aryl, substituted aryl, and substituted alkyl aryl radicals, andR" represents a divalent hydrocarbon radical containing no more than 12cyclic carbon atoms, which radical is selected from the group consistingof arylene, alkyl arylene, substituted arylene, and substituted alkylarylene radicals.

14. The method of claim 13 wherein the lubricant vehicle is a siliconeoil in the lubricating oil range and said silicone oil and said arylcarbamyl compound are heated to a temperature between about 400 F. and450 F. for a period of from about /2 an hour to about 20 hours prior tomilling said mixture.

References Cited in the file of this patent UNITED STATES PATENTS2,041,733 Werntz May 26, 1936 2,070,991 Hund et al. Feb. 16, 19372,468,534 Young et al Apr. 26, 1949 2,547,728 Abrams Apr. 3, 19512,550,746 Wohnsiedler et al May 1, 1951 2,594,286 Bryant et al Apr. 29,1952 2,604,449 Bryant et al July 22, 1952

9. A LUBRICANT GREASE COMPRISING ESSENTIALLY A SILICONE POLYMER OIL INTHE LUBRICATING OIL VISCOSITY RANGE THICKENED WITH FROM ABOUT 5 TO ABOUT70% BY WEIGHT OF N-BENZOYLP-AMINOBENZOIC ACID.